In typhoid fever, the urinary carrier is more dangers than an intestinal carrier

Q. 1 Incorrect statement is:

A

Healthy carriers emerge from subclinical cases

B

The longer the carrier state, the greater the risk to the community

C

Carriers of avirulent organisms are called aseptic carriers

D

In typhoid fever, the urinary carrier is more dangers than an intestinal carrier

Ans.

C

Explanation:

Carriers of avirulent organisms are called aseptic carriers

Carriers of avirulent organisms are called pseudo-carriers. They are not important epidemiologically.

Q. 2

All are true about Typhoid EXCEPT:

A

Incubation period 10 to 14 days

B

Most common among males

C

Carrier are treated by Ampicillin

D

Highest incidence occurs in 30-40 years age group

Q. 2

All are true about Typhoid EXCEPT:

A

Incubation period 10 to 14 days

B

Most common among males

C

Carrier are treated by Ampicillin

D

Highest incidence occurs in 30-40 years age group

Ans.

D

Explanation:

(Highest incidence occurs in 30-40 years age group)

Typhoid Incubation period 10-14 days

Typhoid cause a typhoid ulcer, in the lower ileum and the risk of perforation is highest in 3rd week of typhoid fever. If the muscle sheath is intact, sarcolemmal tubes containing histiocytes appear along the endomysial tube which, in about 3 months, restores properly oriented muscle fibres e.g. in Zenker’s degeneration of the abdominal musculature in typhoid.

To prevent the spread of infection, the patients are kept in isolation till three bacteriologically negative stools and urine reports, are obtained on three separate days.

Recommended periods of isolation

Chicken pox – Until lesions have dried and crusted, or until no new lesions appear, usually by the fifth day.

Measles – For a week from the onset of rash

Mumps – till 5 days after the onset of parotitis

Diphtheria All cases, suspected cases and carriers should be promptly isolated, for at least 14 days or until proved free of infection. At least 2 consecutive nose and throat swabs, taken 24 hours apart, should be negative before termination isolation.

Q. 5

A patient with 14 days of fever is suspected of having typhoid; what investigation should be done:

A

Blood culture

B

Widal

C

Stool culture

D

Urine culture

Q. 5

A patient with 14 days of fever is suspected of having typhoid; what investigation should be done:

A 17 year old adolescent, presented with fever since one week which is step-ladder in pattern. He also has loose stools which are “pea-soup” in consistency. Rose spots are seen on his body. He is most probably infected with:

A

Vibrio cholerae

B

Salmonella typhi

C

Adenovirus

D

Rotavirus

Q. 7

A 17 year old adolescent, presented with fever since one week which is step-ladder in pattern. He also has loose stools which are “pea-soup” in consistency. Rose spots are seen on his body. He is most probably infected with:

A

Vibrio cholerae

B

Salmonella typhi

C

Adenovirus

D

Rotavirus

Ans.

B

Explanation:

Enteric fever is a clinical syndrome characterized by constitutional and gastrointestinal symptoms and by headache.

It can be caused by any Salmonella species.

During the prodromal stage, there is increasing malaise, headache, cough, and sore throat, often with abdominal pain and constipation, while the fever ascends in a stepwise fashion.

The rash (rose spots) commonly appears during the second week of disease. The individual spot, found principally on the trunk, is a pink papule 2–3 mm in diameter that fades on pressure. It disappears in 3–4 days.

Chronic carrier state is associated with presence of bacilli in gall bladder

D

Urinary carrier is more common than fecal carrier

Q. 8

Which of the following is not true regarding Typhoid carrier?

A

Convalescent carriers excrete the organism for 6 – 8 weeks

B

Chronic carriers excrete bacilli for many years

C

Chronic carrier state is associated with presence of bacilli in gall bladder

D

Urinary carrier is more common than fecal carrier

Ans.

D

Explanation:

Fecal carrier is more common than urinary carrier but urinary carrier is more dangerous.

Convalescent Carrier: Sheds typhoid bacilli for 3 or more months after onset of acute illness.

Chronic Carrier: Sheds typhoid bacilli for more than 12 months after onset of acute illness; or has no history of typhoid fever or had the disease more than 1 year previously, but has two feces or urine cultures positive for S. typhi separated by 48 hours.

Other Carrier: Typhoid bacilli have been isolated from surgically removed tissues, organs, or from draining lesions.

Q. 9

Isolation period of an infection is important to control its spread. What is TRUE about isolation period of enteric fever?

A

Till three bacteriologically negative stools and urine reports

B

Upto three days after starting the treatment

C

Till the fever subsides

D

Till Widal becomes negative

Q. 9

Isolation period of an infection is important to control its spread. What is TRUE about isolation period of enteric fever?

A

Till three bacteriologically negative stools and urine reports

B

Upto three days after starting the treatment

C

Till the fever subsides

D

Till Widal becomes negative

Ans.

A

Explanation:

Since typhoid fever is infectious and has a prolonged course, the cases are better transferred to a hospital for proper treatment, as well as to prevent the spread of infection.

As a rule,cases should be isolated till three bacteriologically negative stools and urine reports, are obtained on three separate days.

A patient presents with fever for 3 weeks. On examination he is observed to have Splenomegaly. Ultrasonography reveals a hypoechoic shadow in spleen near the hilum. Gram negative bacilli are isolated on blood culture. Which of the following is the most likely causative organism?

A

Cytomegalovirus

B

Toxoplasmosis

C

Salmonella

D

Lymphoma virus

Q. 10

A patient presents with fever for 3 weeks. On examination he is observed to have Splenomegaly. Ultrasonography reveals a hypoechoic shadow in spleen near the hilum. Gram negative bacilli are isolated on blood culture. Which of the following is the most likely causative organism?

A

Cytomegalovirus

B

Toxoplasmosis

C

Salmonella

D

Lymphoma virus

Ans.

C

Explanation:

Only salmonella is a bacteria, toxoplasmosis is a parasite,other options given are viruses.

so this question just need general knowledge to answer no need to explain.

Ref: Harrison’s Internal Medicine, 17th Edition, Page 458, 812

Q. 11

Which of the following statement regarding typhoid in children is false?

A

Splenomegaly may be seen

B

Neutropenia may be present

C

Urine and stool culture may show the organism after 2 weeks of illness

D

Relative bradycardia is invariably seen in children

Q. 11

Which of the following statement regarding typhoid in children is false?

A

Splenomegaly may be seen

B

Neutropenia may be present

C

Urine and stool culture may show the organism after 2 weeks of illness

D

Relative bradycardia is invariably seen in children

Ans.

D

Explanation:

Relative bradycardia is not always present in a child with typhoid fever.

Typhoid is diagnosed using blood culture which is positive during the 1st week of illness, urine culture during 2nd or 3rd week or using widal test during 3rd week of illness.

Ref: Textbook of Microbiology By Ananthanarayan, 8e page 296.

Q. 12

Pea-soup stool is characteristically seen in â€‘

A

Cholera

B

Typhoid

C

Botolism

D

Polio

Q. 12

Pea-soup stool is characteristically seen in â€‘

A

Cholera

B

Typhoid

C

Botolism

D

Polio

Ans.

B

Explanation:

Ans. is ‘b’ i.e., Typhoid

Pea – soup stool

It is khaki – green, slimy stools typically occurs in the 3′ week of typhoid fever, at which point the patients are in toxic state and at greatest risk for the intestinal perforation and hemorrhage.

Similar stools occur in enteropathogenic E. coli infection of infants.

Q. 13

All of the following are true regarding typhoid exceptâ€‘

A

Urinary carriers are more dangerous

B

Vi ab is used for detecting carrier

C

Vi is seen in normal population

D

Urine carrier is associated with anomalies

Q. 13

All of the following are true regarding typhoid exceptâ€‘

A

Urinary carriers are more dangerous

B

Vi ab is used for detecting carrier

C

Vi is seen in normal population

D

Urine carrier is associated with anomalies

Ans.

C

Explanation:

Ans. is ‘c’ i.e., Vi seen in normal population

. Vi Antigen is not seen in normal population. It appears only after infection.

Carriers

. Bacilli presist in the gall bladder or kidney and are eliminated in the feces (fecal carriers) or urine (urinary carrier), respectively.

. The development of the carrier state is more common in women and in older age groups ( over 40 yrs)

. Carriers are the more frequent source of infection than cases.

. Urinary carriage is less frequent but more dangerous than intestinal carrier – Park PSM

. Urinary carrier is generally associated with some urinary lesions such as calculi or schistosomiasis.

. Presence of Vi antibody indicates the carrier state.

. Carriers may be following types :-

Q. 14

Diagnosis of typhoid in the first week is by –

A

Widal test

B

Stool culture

C

Urine culture

D

Blood culture

Q. 14

Diagnosis of typhoid in the first week is by –

A

Widal test

B

Stool culture

C

Urine culture

D

Blood culture

Ans.

D

Explanation:

Ans. is ‘d’ i.e., Blood culture

Q. 15

In a patient with typhoid, diagnosis after 15 days of onset of fever is best done by –

A

Blood culture

B

Widal

C

Stool culture

D

Urine culture

Q. 15

In a patient with typhoid, diagnosis after 15 days of onset of fever is best done by –

A

Blood culture

B

Widal

C

Stool culture

D

Urine culture

Ans.

B

Explanation:

Ans:B.)Widal

Lab Diagnosis for Typhoid Fever

CBC shows:

Low TLC, leucopenia.

Blood culture, positive in the first week of infection in 80 % of the cases. But blood culture decreases to 50% in the third week.

Blood culture is considered 100 % specific.

Buffy coat may decrease the time for isolation.

This is subcultured on the MacConkey media.

Bone marrow culture if taken will be positive and may have high yield up to 90% sensitivity.

Stool culture will be a positive but not reliable test. This will be positive within the first 7 days of infection.

This is negative in 60 to 70% of the cases during the first week. If this patient is untreated then positive in these patients in the third week.

The chronic carrier may have stool culture positive even up to one year.

Feces cultures on solid selective media:

Desoxycholate citrate agar where there are non-lactose fermenting colonies.

Macconkey medium shows non-fermenting colonies.

There is no gas and no fermentation of the sugar.

Widal test will be positive after 7 to 10 days of infection.

Typhidot test claimed by the manufacturing companies that it will be positive after 2 to 3 days.

The urine culture may be done and is positive in case of enteric fever but is less sensitive.

This is also done on the MacConkey media

Q. 16

A 24 year-old cook in a hostel mess suffered from enteric fever 2 years back. The chronic carrier state in this patient can be diagnosed by –

A

Vi agglutination test.

B

Blood Culture in Brain Heart infusion broth

C

Widal test

D

All

Q. 16

A 24 year-old cook in a hostel mess suffered from enteric fever 2 years back. The chronic carrier state in this patient can be diagnosed by –

A

Vi agglutination test.

B

Blood Culture in Brain Heart infusion broth

C

Widal test

D

All

Ans.

A

Explanation:

Ans. is ‘a’ i.e., Vi agglutination test

Diagnosis of carrier

. The demonstration of Vi agglutinins indicate the carrier state. While this is useful as a screening test confirmation should be made by culture.

. Diagnosis of carriers

. Screening test Demonstration of Vi agglutinins

. Definitive diagnosis Culture

– In fecal carriers from feces or by duodenal aspiration – In urinary carriers from urine

Q. 17

True statement about Widal test in typhoid isâ€‘

A

0-antigen titre remains positive for several months & reaction to it is rapid

B

H-antigen titre remains positive for several months & reaction to it is rapid

C

Both remain positive for several months & reaction to both is rapid

D

None

Q. 17

True statement about Widal test in typhoid isâ€‘

A

0-antigen titre remains positive for several months & reaction to it is rapid

B

H-antigen titre remains positive for several months & reaction to it is rapid

C

Both remain positive for several months & reaction to both is rapid

D

None

Ans.

B

Explanation:

Ans. is ‘b’ i.e., H-antigen titre remains positive for several months and reaction to it is rapid

Q. 18

True statement about widal test in typhoid is-(

A

Widal test is confirmative in endemic areas

B

Antibiotic treatment does not alter widal test results

C

Previous infection alters widal test

D

Widal test does not alter with prior vaccination

Q. 18

True statement about widal test in typhoid is-(

A

Widal test is confirmative in endemic areas

B

Antibiotic treatment does not alter widal test results

C

Previous infection alters widal test

D

Widal test does not alter with prior vaccination

Ans.

C

Explanation:

Ans. is ‘c’ i.e., Previous infection alters widal test

. Person who have had prior infection or immunization may develop an anamnestic response during unrelated fever and may show false positive reaction. This may be differentiated by repetition of test after a week. The anamnestic response shows only a transient rise, while in enteric fever the rise is sustained.

About other options :

. Cases treated with antibiotic (cholermphenicol) may show a poor agglutinin response.

. Other than a positive culture, no specific laboratory test is diagnostic –

. Vi polysaccharide bound to a nontoxic recombinant protein that is identical to pseudomonas aeruginosa exotoxinA

Features of vaccines

. 3 year efficacy is maximum with whole cell vaccine.

. 1 year efficacy is same with all these three vaccines.

. Whole cell vaccine is associated with a much higher incidence of adverse effects.

. The only recommondation for domestic vaccination include people who have intimate or house hold contact with a chronic carrier or laboratory workers who frequently work with S. typhi

. Because of their similar short term efficacy and low incidence of side effects, the current bias is toward the use of Ty2 la or ViCPS for vaccination of travellers.

Q. 21

Carriers of Salmonella typhi can be detected by â€‘

A

Widal test

B

Blood culture

C

Sputum culture

D

Culture of feces

Q. 21

Carriers of Salmonella typhi can be detected by â€‘

A

Widal test

B

Blood culture

C

Sputum culture

D

Culture of feces

Ans.

D

Explanation:

Ans. is ‘d’ i.e., Culture of feces

. Identification of fecal carriers is by isolation of the bacillus from feces or from bile.

. Identification of urinary carriers is by isolation of the bacillus from urine.

Q. 22

Typhoid carriers are detected by following except â€‘

A

Isolation of bacteria from urine

B

Isolation of bacteria from bile

C

Vi antigen

D

Widal test

Q. 22

Typhoid carriers are detected by following except â€‘

A

Isolation of bacteria from urine

B

Isolation of bacteria from bile

C

Vi antigen

D

Widal test

Ans.

D

Explanation:

Ans. is ‘d’ i.e., Widal test

Q. 23

True about typhoid is –

A

Incubation period 3-6 weeks

B

Chronic carrier is 10-15%

C

Widal test is specific

D

Vi polysaccharide of bacterial cell used for vaccination

Q. 23

True about typhoid is –

A

Incubation period 3-6 weeks

B

Chronic carrier is 10-15%

C

Widal test is specific

D

Vi polysaccharide of bacterial cell used for vaccination

Ans.

D

Explanation:

Ans. is ‘d’ i.e., Vi polysaccharide of bacterial cell used for vaccination

Q. 24

Man is the only reservoir of –

A

Rabies

B

Measles

C

Typhoid

D

b and c

Q. 24

Man is the only reservoir of –

A

Rabies

B

Measles

C

Typhoid

D

b and c

Ans.

D

Explanation:

Ans. is ‘b’ i.e., Measles; ‘c’ i.e., Typhoid

Measles

The only source of infection is a case of measles. Carriers are not known to occur. There is some evidence to suggest that subclinical measles occurs more often than previously thought.

Typhoid

Man is the only known reservoir of infection, case or carrier.

Rabies

– In urban Rabies dog acts as a reservoir.

– In Wild-life rabies jackal , fox and other animals act as reservoir.

Japanese Encephalitis

Animal and birds act as reservoir.

Q. 25

All are true regarding typhoid ulcer except â€‘

A

Perforation is less common in children below 5yrs

B

Placed transversely along the ileum

C

Multiple ulcer found in terminal ileum

D

Perforation occurs in 3rd week

Q. 25

All are true regarding typhoid ulcer except â€‘

A

Perforation is less common in children below 5yrs

B

Placed transversely along the ileum

C

Multiple ulcer found in terminal ileum

D

Perforation occurs in 3rd week

Ans.

B

Explanation:

Ans. is ‘b’ i.e., Placed transversely along the ileum

o Typhoid ulcers are placed longitudinally along the ileum.

o On the other hand. Tubercular ulcers are placed transversely along the ileum (Mnemonic: (neck) tie lies longitudinal on body).

Features of Tvhoid ulcer â€‘

Salmonella typhi primarily affects the ileum and colon, the terminal ileum is affected most often. o The peyer’s patches show ovoid ulcers with their long axes along the axis of the ileum (remember that in intestinal tuberculosis, the ulcers are transverse to the axis of the bowel).

o The margins of the ulcer are slightly raised, and the base of the ulcers is base black due to sloughed mucosa.

o Though the enteric fever is an example of acute inflammation neutrophils are invariably absent from cellular

infiltrate and this is reflected in leucopenia with neutropenia and relative lymphocytosis in peripheral blood. The

o Reservoir -4 Man is the only reservoir. Carriers are more important than cases.

o Source of infection

Primary —> Feces, Urine

Secondary —> Water, food, fingers, flies.

o Age Highest incidence occurs in the 5-19 years of age group.

o Sex Males > Females

o Incubation period —> 10-14 days.

Treatment

Cases –> Ciprofloxacin is the DOC.

Carriers -4 Amoxicillin or ampicillin with cholecystectomy.

Q. 35

Incubation period of typhoid –

A

3-20 days

B

14-45 days

C

5-10 days

D

15-60 days

Q. 35

Incubation period of typhoid –

A

3-20 days

B

14-45 days

C

5-10 days

D

15-60 days

Ans.

A

Explanation:

Ans. is ‘a’ i.e., 3-20 days

o This question is somewhat tricky one for PGI Chandigarh, because more than one options can be correct.

“Usually incubation period is 10-14 days. But it may be short as 3 days or as long as three weeks depending upon the dose of the bacilli ingested” – Park

o So, for PGI Chandigarh more than one options may be correct as in this question.

Option ‘a’ —> 3 days to 3 weeks (20 days)

Q. 36

In typhoid a permanent carrier is one who excretes bacilli for more than –

A

3 months

B

6 months

C

1 year

D

3 years

Q. 36

In typhoid a permanent carrier is one who excretes bacilli for more than –

A

3 months

B

6 months

C

1 year

D

3 years

Ans.

C

Explanation:

Ans. is ‘c’ i.e., 1 year

o Bacilli presist in the gall bladder or kidney and are eliminated in the feces (fecal carriers) or urine (Urinary carrier), respectively.

o The development of the carrier state is more common in women and in older age groups ( over 40 yrs)

o Carriers are the more frequent source of infection than cases.

o Urinary carriage is less frequent but more dangerous than intestinal carriers.

o Note —> Permanent carriers are amongst the chronic carriers.

Q. 37

Risk factor for cholangiocarcinoma all except:

A

Chronic typhoid carrier

B

Chronic ulcerative colitis

C

Parasitic infestation

D

Choledocholithiasis

Q. 37

Risk factor for cholangiocarcinoma all except:

A

Chronic typhoid carrier

B

Chronic ulcerative colitis

C

Parasitic infestation

D

Choledocholithiasis

Ans.

D

Explanation:

Ans is ‘d’ i.e. Choledocholithiasis

Q. 38

A 25 years old female presents with pyrexia for ten days, develops acute pain in periumblical region spreading all over the abdomen. What would be the most likely cause ?

A

Perforation peritonitis due to intestinal tuberculosis

B

Generalised peritonitis due to appendicular perforation

C

Typhoid enteric perforation and peritonitis

D

Acute salpingo-oophoritis with peritonitis

Q. 38

A 25 years old female presents with pyrexia for ten days, develops acute pain in periumblical region spreading all over the abdomen. What would be the most likely cause ?

A

Perforation peritonitis due to intestinal tuberculosis

B

Generalised peritonitis due to appendicular perforation

C

Typhoid enteric perforation and peritonitis

D

Acute salpingo-oophoritis with peritonitis

Ans.

C

Explanation:

Ans. is ‘c’ i.e., Typhoid enteric perforation and peritonitis

Q. 39

Typhoid perforation is diagnosed by-

A

Plain X-ray of abdomen in erect posture

B

Rectal examination

C

Gastric aspiration

D

Barium enema

Q. 39

Typhoid perforation is diagnosed by-

A

Plain X-ray of abdomen in erect posture

B

Rectal examination

C

Gastric aspiration

D

Barium enema

Ans.

A

Explanation:

Ans. is ‘a’ i.e., Plain X-ray of abdomen in erect posture

Q. 40

Sonu, a 15 years old girl, a regular swimmer presents with sudden onset of pain in abdomen, abdominal distension and fever of 39° C and obliteration fo the liver dullness. Most probable diagnosis is â€‘

A

Ruptured typhoid ulcer

B

Primary bacterial peritonitis

C

Ruptured ectopic pregnancy

D

UTI with PID.

Q. 40

Sonu, a 15 years old girl, a regular swimmer presents with sudden onset of pain in abdomen, abdominal distension and fever of 39° C and obliteration fo the liver dullness. Most probable diagnosis is â€‘

A

Ruptured typhoid ulcer

B

Primary bacterial peritonitis

C

Ruptured ectopic pregnancy

D

UTI with PID.

Ans.

A

Explanation:

Ans. is ‘a’ ie. Ruptured typhoid ulcer

The clue to this answer is presence of this clinical sign in the pt. —) Obliteration of liver dullness.

Obliteration of liver dullness :

Right mid-axillary line is percussed from above downwoards. The percussion note will be resonant in the upper part of the mid-axillary line. At the upper border of the liver the resonant note in replaced by the dull note.

If the liver dullness is replaced by a resonant note it indicates presence of free gas under the diaphragm as occurs in the perforation of the gastro-intestinal tract.” – S.Das Manual, 4/e, p344

No other condition is able to cause obliteration of liver dullness.

Q. 41

Features of Typhoid Ulcers include all of the following Except:

A

Bleeding

B

Perforation

C

Stricture and obstruction

D

Longitudinal orientation

Q. 41

Features of Typhoid Ulcers include all of the following Except:

A

Bleeding

B

Perforation

C

Stricture and obstruction

D

Longitudinal orientation

Ans.

C

Explanation:

Answer is C (Stricture and obstruction)

Strictures and obstruction do not occur in typhoid ulcers.

`Typhoid Ulcers heal without significant scarring in patients that recover and hance do not produce strictures or intestinal obstruction’ — Gastrointestinal Pathology

Characteristic Features of Typhoid Ulcers

Most common site is mucosa of small intestine (Ileum) in region of lymphoid patches (Payer’s patches)

Ulcers are oval

Ulcers are arranged longitudinally (Longitudinal ulcers)Q

Lie in the long axis of the intestine along the antimesenteric border

Ulcers may be single or multiple

Ulcers may erode and cause complications (Bleeding/perforation) Q

– Bleeding

– Perforation

Ulcers heal without significant scarring or fibrosis in patients who recover

– Strictures and intestinal obstruction almost never occurs.

Q. 42

Longitudinal ulcers in the intestine are seen in:

September 2008

A

Tuberculosis

B

Typhoid

C

Amoebiasis

D

Yersinia

Q. 42

Longitudinal ulcers in the intestine are seen in:

September 2008

A

Tuberculosis

B

Typhoid

C

Amoebiasis

D

Yersinia

Ans.

B

Explanation:

Ans. B: Typhoid

In typhoid fever there is at first a general swelling of the Peyer’s patch; it is an inflammatory swelling accompanied by abundant infiltration of leucocytes which occupy both the closed follicles and the mucous membrane. As the time goes on the whole tissue gets more and more infiltrated with leucocytes, and the raised patch gets more solid and its surface more homogeneous.

On this condition follows Necrosis. The infiltrated and altered patch or solitary follicles forms a slough, of larger or smaller size.

Mucosal shedding creates oval ulcers, oriented along the long axis of the ileum, that may perforate. Serpentine, elongated ulcers, oriented along the long axis of bowel is seen in Crohn’s disease.

Q. 43

Enteric fever diagnosis in 2nd week is best made by:

September 2012

A

Blood

B

Widal test

C

Stool

D

Widal

Q. 43

Enteric fever diagnosis in 2nd week is best made by:

September 2012

A

Blood

B

Widal test

C

Stool

D

Widal

Ans.

B

Explanation:

Ans. B i.e. Widal test

Widal test

It is a presumptive serological test for enteric fever or undulant fever whereby bacteria causing typhoid fever are mixed with serum containing specific antibodies obtained from an infected individual.

In case of Salmonella infections, it is a demonstration of the presence of 0-soma false-positive result.

Test results need to be interpreted carefully in the light of past history of enteric fever, typhoid vaccination, and the general level of antibodies in the populations in endemic areas of the world.

As with all serological tests, the rise in antibody levels needed to perform the diagnosis takes 7-14 days, which limits it applicability in early diagnosis.

Other means of diagnosing Salmonella typhi (and paratyphi) include cultures of blood, urine and faeces.

These organisms produce H2S from thiosulfate and can be easily identified on differential media such as Bismuth sulfite agar.

Often 2-mercaptoethanol is added to the Widal test.

This agent more easily denatures the IgM class of antibodies, so if a decrease in the titer is seen after using this agent, it means that the contribution of IgM has been removed leaving the IgG component.

This differentiation of antibody classes is important; as it allows for the distinction of a recent (IgM) from an old infection (IgG).

The Widal test is positive if TO antigen titer is more than 1:160 in an active infection, or if TH antigen titer is more than 1:160 in past infection or in immunized persons.

A single Widal test is of little clinical relevance due to the number of cross reacting infections, including malaria.

If no other tests (either bacteriologic culture or more specific serology) are available, a fourfold increase in the titer (e.g., from 1:40 to 1:160) in the course of the infection, or a conversion from an IgM reaction to an IgG reaction of at least the same titer, would be consistent with a typhoid infection.

In this test the patient’s serum is tested by tube agglutination test for its titres of antibodies against H,0 and Vi suspensions

of enteric fever bacteria that are commonly encountered in an area such as S.typhi and S. paratyphiA.

False positives

Immunization with typhoid vaccine Repeated subclinical infection

Past clinical infection

Healthy carriers of S. typhi

Anamnestic response

Patients of cirrhosis and hepatitis False negatives

Too early collection of blood sample Patients on antibiotics

5-10% patients do not respond by antibody formation

Immunosuppressed patients

Q. 45

Enteric fever is caused by:

September 2005

A

Salmonella typhi

B

Salmonella paratyphi A

C

Salmonella paratyphi B

D

All of the above

Q. 45

Enteric fever is caused by:

September 2005

A

Salmonella typhi

B

Salmonella paratyphi A

C

Salmonella paratyphi B

D

All of the above

Ans.

D

Explanation:

Ans. D: All of the above

Typhoid fever is caused by Salmonella typhi.

Paratyphoid fever is caused by Salmonella paratyphi A, B and C.

The term enteric fever encompasses both typhoid and paratyphoid fevers.

Q. 46

Most immunogenic in typhoid is:

March 2011

A

O antigen

B

H antigen

C

Vi antigen

D

M antigen

Q. 46

Most immunogenic in typhoid is:

March 2011

A

O antigen

B

H antigen

C

Vi antigen

D

M antigen

Ans.

B

Explanation:

Ans. B: H antigen

The H antigen is strongly immunogenic and induces antibody formation rapidly and in high titres following infection or immunization Somatic (O) or Cell Wall Antigens

They are heat stable and alcohol resistant.

Surface (Envelope) Antigens

Commonly observed in other genera of enteric bacteria (e.g., Escherichia coli and Klebsiella), may be found in some Salmonella serovars.

Surface antigens in Salmonella may mask O antigens, and the bacteria will not be agglutinated with O antisera. One specific surface antigen is well known: the Vi antigen.

Vi antigen

The Vi antigen occurs in only three Salmonella serovars (out of about 2,200): Typhi, Paratyphi C, and Dublin.

Strains of these three serovars may or may not have the Vi antigen.

Flagellar (H) Antigens

Flagellar antigens are heat-labile proteins.

Strongly immunogenic; induces antibody formation rapidly and in high titres following infection or immunization

Mixing salmonella cells with flagella-specific antisera gives a characteristic pattern of agglutination (bacteria are loosely attached to each other by their flagella and can be dissociated by shaking).

A few Salmonella enterica serovars (e.g., Enteritidis, Typhi) produce flagella which always have the same antigenic specificity. Such an H antigen is then called monophasic.

Most Salmonella serovars, however, can alternatively produce flagella with two different H antigenic specificities. The H antigen is then called diphasic.

Q. 47

All are true regarding typhoid ulcer EXCEPT:

September 2012

A

Ileum is the common site

B

Bleeding is common

C

Stricture is usual and causes obstruction

D

Perforation is common

Q. 47

All are true regarding typhoid ulcer EXCEPT:

September 2012

A

Ileum is the common site

B

Bleeding is common

C

Stricture is usual and causes obstruction

D

Perforation is common

Ans.

C

Explanation:

C i.e. Stricture is common and causes obstruction

Typhoid ulcers

Longitudinal,

Ulceration of Peyer’s patches,

Stricture is rare

Q. 48

Typhoid ulcer perforation mostly occurs in:

March 2005, March 2013

A

1 -2 week

B

2 -3week

C

3-4 week

D

4 -5week

Q. 48

Typhoid ulcer perforation mostly occurs in:

March 2005, March 2013

A

1 -2 week

B

2 -3week

C

3-4 week

D

4 -5week

Ans.

C

Explanation:

Ans. C: 3-4 week

The mechanism is hyperplasia and necrosis of Peyer’s patches of the terminal ileum.

The lymphoid aggregates of Peyer’s patches extend from the lamina propria to the submucosa, so that in the presence of hyperplasia the distance from the luminal epithelium to the serosa is bridged by lymphoid tissue.

During the course, S. Typhi is found within mononuclear phagocytes of Peyer’s patches, and in cases with intestinal perforation, both this tissue and surrounding tissues show hemorrhagic areas, most often during the third and the fourth week of the illness. Tissue damage in Peyer’s patches occurs, resulting in ulceration, bleeding, necrosis, and, in extreme cases, full-thickness perforation.

Q. 49

Which of the following is best for diagnosing typhoid in the first week:

March 2007

A

Stool culture

B

Blood culture

C

Urine culture

D

Widal test

Q. 49

Which of the following is best for diagnosing typhoid in the first week:

March 2007

A

Stool culture

B

Blood culture

C

Urine culture

D

Widal test

Ans.

B

Explanation:

Ans. B: Blood culture

Salmonella is a Gram-negative, non spore forming, facultative anaerobic short bacillus that is motile due to its peritrichous flagella. The bacterium grows best at 37°C (human body temperature).

Typhoid fever is characterized by a sustained fever as high as 40°C (104°F), profuse sweating, gastroenteritis, and nonbloody diarrhea. Less commonly a rash of flat, rose-colored spots may appear.

In the first week, there is a slowly rising temperature with relative bradycardia. There is leukopenia with eosinopenia and relative lymphocytosis, a positive diazo reaction and blood cultures are positive for Salmonella Typhi or Paratyphi. The classic Widal test is negative in the first week.

In the second week of the infection, the patient lies prostrated with high fever in plateau around 104°F (40°C) and bradycardia (Sphygmo-thermic dissociation), classically with a dicrotic pulse wave. Delirium is frequent. This delirium gives to typhoid the nickname of “nervous fever”. Rose spots appear on the lower chest and abdomen in around 1/3 patients. There are rhonchi in lung bases.

Diarrhea can occur in this stage: green with a characteristic smell, comparable to pea-soup. The spleen and liver are enlarged (hepatosplenomegaly). The Widal reaction is strongly positive with anti 0 and anti H antibodies. Blood cultures are sometimes still positive at this stage.

In the third week of typhoid fever a number of complications can occur:

Intestinal hemorrhage due to bleeding in congested Peyer’s patches; this can be very serious but is usually non-fatal. Intestinal perforation in distal ileum: this is a very serious complication and is frequently fatal.

Encephalitis

Metastatic abscesses, cholecystitis, endocarditis and osteitis

The yield of blood cultures is variable; sensitivity is as high as 90% during the first week of infection and decreases to 50% by the third week.

Q. 50

Regarding typhoid ulcer, all of the following are true except:

March 2005

A

Perforation is common

B

Obstruction results due to stricture formation

C

Bleeding is usual

D

Ileum is the common site

Q. 50

Regarding typhoid ulcer, all of the following are true except:

March 2005

A

Perforation is common

B

Obstruction results due to stricture formation

C

Bleeding is usual

D

Ileum is the common site

Ans.

B

Explanation:

Ans. B: Obstruction results due to stricture formation

Typhoid ulcers may bleed or perforate, usually during lysis.

Most perforations are near the ileocecal valve, measure less than 1 cm across, and lead to peritonitis. These areas become repopulated with lymphoid cells and heal without scarring.

Q. 51

Enteric fever is caused by â€‘

A

S typhi

B

S paratyphi A

C

S paratyphi C

D

All of the above

Q. 51

Enteric fever is caused by â€‘

A

S typhi

B

S paratyphi A

C

S paratyphi C

D

All of the above

Ans.

D

Explanation:

Ans. is ‘d’ i.e., All of the above

Enteric fever

The term enteric fever includes typhoid fever caused by S.typhi and paratyphoid fever caused by S. paratyphi A, B and C.

The ability to resist intracellular killing and to multiply with in these cells is a measure of virulence of salmonella.

The incubation period for S. typhi ranges from 3 to 21 days.

Most prominant symptom of this systemic infection is prolonged fever. (Step-ladder pyrexia).